The present invention relates to an apparatus for automatically removing sealing plugs, stoppers or caps (hereinafter referred to as plugs) from drawn blood tubes or test tubes (hereinafter referred to as containers) at the time of clinical or laboratory examination and also a method therefor.
In the field of clinical examination, open drawn blood tubes and vacuum drawn blood tubes have been widely used as containers for materials to be tested or examined such as blood (hereinafter referred to as samples). A sample drawn and collected by a syringe is in general poured into an open drawn blood tube and kept therein being closed and sealed with a plug or cap. In this case, the tube (the container) does not have to keep the the sample in a vacuumed state, and the container and plug are usually made of plastic such as polyethylene or the like. A sample that must be kept in a vacuumed state is contained in a vacuum tube, and a rubber plug or the like is used in order to stably maintain the vacuumed state within the tube for a long time.
In advance of removal of a plug from of a container for analysis, a collected sample needs to be put in a centrifuge to separate the components thereof. There have been automatic plug removing methods using apparatus as well as manual plug removal by a person's hands at work. For example, Japanese Laid-Open Patent Publication No.263558/1989 (Tokukaihei 1-263558) discloses an automatic plug removing apparatus having a cap holding down member with a recess. In this apparatus, a cap provided on a drawn blood tube is fitted into the recess of the apparatus and the cap holding down member is actuated to apply a twist and the like to the cap in the recess so as to loosen the seal between the cap and the drawn blood tube and then the cap is removed from the tube.
The centrifuging process and transportation prior to the plug removal usually cause samples to adhere to a plug on the container. Such sample adhering to the plug might scatter due to a shock at the time of removing the plug from the container or might drop down due to swinging, vibration or the like at the time of disposal. Such scatter or drops of the sample may inadvertently enter other containers and end up with contamination of samples in the other containers. As a result, correct analysis for the respective samples can not be obtained even if high-accuracy analysis is conducted. Such contamination causes a serious error in the results of clinical examination and the like, and therefore must be absolutely avoided.
Manual plug removal by a person at work tends to cause injury, infection to the person due to the scatter of samples, and contamination of samples in other containers.
In order to avoid scattering and splashing of samples, some of conventional automatic plug removing apparatus provide improved arrangements. For example, one gives a twist or a circular arc oscillating movement to a plug and then removes it from a container with a lighter force, or another reduces a plug removing speed just before a plug is removed away from a container. There is another apparatus which has a dish for receiving and collecting liquid drops from a plug in order to prevent inadvertent sample drops at the time of disposing the plug. However, these conventional apparatus fail to prevent samples from scattering or splashing completely. Especially when a plurality of containers are simultaneously put under the plug removing process on a batch basis, complete prevention of contamination cannot be obtained by the conventional apparatus.